Atomic structure and the periodic table Flashcards
Define the term atom
The smallest part of an element that can exist. It has no electrical charge and is made up of a nucleus containing particles which are protons and neutrons as well as electrons in energy levels.
Measured in nanometers
Define the term proton
A positively charged particle found in the nucleus of an atom
Define the term neutron
A neutral particle found in the nucleus of an atom
Define the term electron
A negatively charged particle which are found in energy levels (Shells) around the nucleus of an atom
What is a nanometer
1 x 10 to the power -9 metres
What is the atomic number of an element
It is the number of protons contained in the nucleus of an element
What is the mass number of an element
It is the combined number of protons and neutrons contained in the nucleus of an element
What is an isotope?
An isotope is an atom with the same number of protons but a different number of neutrons
eg carbon exists as C12, C13 and C14
they all have 6 protons but have 6,7 and 8 neutrons respectively.
What is an ion?
It is a particle which has an electric charge because it does not have the same number of protons and electrons
eg CL- which has one more electron than protons and Mg2+ which has two more protons than electrons.
TIP - there is a direct relationship between the ionic structure of an element and its position on the periodic table.
Describe the gold foil experiment carried out by Geiger and Marsden in 1909
They directed a beam of alpha (He2+) particles which travel very quickly through a thin sheet of gold . They expected all of the particles to pass through but a small number were deflected and bounced back.
How did Rutherford explain the results of the gold foil experiment
He suggested that the deflection of the alpha particle was due to an electrostatic charge between the particle and a very small charged nucleus, he also said the nucleus could be massive.. He said that the nucleus may be either positively or negatively charged. A positive charged nucleus would deflect the positively charged alpha particle away whereas a negatively charged one would pull the particle toward and around it.
How is the gold foil experiment explained nowadays.
The diameter of the nucleus of an atom is tiny in comparison to the atom 1:20000. The nucleus is positively charged. Most of the alpha particles pass through the gold atom. A few hit the nucleus and were deflected back as the positive charges repelled each other. Some came near the nucleus and were deflected slightly. .
Who suggested the plum pudding model for the atom after discovering electrons and when was that?
J J Thompson in 1897.
What did James Chadwick discover in 1932
That there are neutrons in the nucleus of an atom.
Who suggested that electrons orbit the nucleus at specific distances in 1913?
Neils Bohr
What is the name for a substance which is made from only one type of atom
element
What is meant by the term relative atomic mass?
It is the average mass of all of the isotopes of an element.
What are the four parts of each box on the periodic table in the correct order
- relative atomic mass
- Symbol
- Name
- Atomic number.
Describe the properties of a metal
- High melting and boiling points
- Electrical and thermal conductor
- High density
- Malleable- can be hammered into shape
- Ductile- can be drawn into a wire
- Form positive ions in ionic compounds
- Usually shiny in appearance.
Describe the properties of a non metal
- Low melting and boiling points
- Not an electrical or thermal conductor- except graphite
- Low density
- Not malleable- brittle so cannot be hammered into shape
- Not ductile- cannot be drawn into a wire
- Form negative ions in ionic compounds
- Usually not shiny (dull) in appearance
Some elements are quite difficult to classify as either metal or non metal as they have characteristics of both, name two
Boron
Silicon
Germanium
How are elements placed in the periodic table?
It depends on how many protons they have eg in increasing atomic number
The periodic table has rows and columns but they are called by alternative names, what are they?
Rows = periods Columns = groups
What is a compound?
A substance which is made from 2 or more different elements which are chemically bonded.
What characteristic is shared by all of the elements in a group?
They all have the same number of electrons in their outer shell.
What are the names given to all of the elements in the first column of the periodic table?
The group 1 or alkali metals
What are the main characteristics of the alkali metals
- They all form ions with one more proton so +1 eg Li+
- They all have one electron in their outer shell which they can lose easily- therefore
- They are all very reactive and are stored in oil to stop them reacting with water and oxygen in the air
- They are all soft and can be cut with a knife
